molecular genetics

Question 1

stages of a gene

Answer 1

nucleotide > DNA> Chromosome> gene

Question 2

What is a nucleotide?

Answer 2

Nucleotides are the basic units of DNA. Each nucleotide consists of a phosphate group, deoxyribose sugar, and a nitrogenous base. There are 4 types of nitrogenous bases, adenine(A),
thymine(T) , guanine(G), Cytosine(C).

Question 3

Describe the structure of DNA

Answer 3

DNA is a large molecule/ polymer made of smaller units called nucleotides

Nucleotides are the basic units of DNA. Each nucleotide consists of a phosphate group, deoxyribose sugar, and a nitrogenous base. There are 4 types of nitrogenous bases, adenine(A),
thymine(T) , guanine(G), Cytosine(C).

DNA is made up of two anti-parallel polynucleotide strands, forming a double helix structure

olevel 6 marks qn

Question 4

What is a Chromosome?

Answer 4

condensed DNA wrapped around proteins

Question 5

Define a gene

Answer 5

Genes are sequences of nucleotides that code for a specific polypeptide

Question 6

what is a polynucleotide

Answer 6

nucleotides that are joined together to form a long chain called polynucleotides

Question 7

Which base does Adenine bond with?

Answer 7

Adenine always bonds with thymine,

Question 8

Which base does Guanine bond with?

Answer 8

Guanine always bonds with Cytosine,

Question 9

Stages from a nucleotide to a gene

Question 10

What is transcription

Answer 10

• occurs in the nucleus
• DNA unwinds and a template strand is used to make mRNA, mRNA moves out of the nucleus into the cell cytoplasm

Question 11

What is mRNA?

Answer 11

MRNA stands for “messenger RNA”
it is a single stranded polynucleotide

> DNA is 2 anti parallel structure, mRNA is one of the two parts split

Question 12

What is Translation?

Answer 12

-occurs in the cytoplasm
- ribosomes in the cytoplasm or the RER will bind to mRNA and use the codons on the mRNA to make polypeptides

Question 13

Process of translation

Answer 13

• mRNA binds to the ribosome
• the codons are read (each codon is three nucleotides)
• tRNA molecules that are floating around in the cytoplasm will bind to the ribosome
• if the anti-codon on the mRNA molecule matches the tRNA molecule , the tRNA molecule will leave behind their amino acid.
• as the ribosome continues reading the mRNA molecule, the amino acid chain will grow longer, until the process is finished.

Question 14

What is tRNA?

Answer 14

tRNA, stands for “transfer RNA”

Question 15

DNA nucleotide vs RNA nucleotide

Answer 15

inside the nucleus vs in the cytoplasm

Phosphate grp–> deoxyribose vs ribose

4nitrogenous bases–> Adenine, thymine, guanine, cytosine vs adenine, uracil , guanine, cytosine

DNA is double stranded vs RNA is single stranded

before the ‘vs’ is for DNA nucleotide, after the ‘vs’ RNA nucleotide

Question 16

olevel MCQ:
Which molecule has its synthesis directly controlled by DNA?
A) Amylase
B) Glycerol
C) Glycogen
D) Iron

Answer 16

Ans: A: Amylase
Amylase is am enzyme. it is a protein
Glycerol is a triol (alcohol with three hydroxyl groups)
Glycogen is a carbohydrate made up of numerous glucose molecules

Question 17

What are the 4 stages of a cells life?

Answer 17

Growth, DNA synthesis, Growth and preparation for mitosis, mitosis

https://drive.google.com/file/d/1b_EtKqgC4kKvD5HLW8HkQuKTH1CemWm3/view?usp=drivesdk

Question 18

When do chromosomes replicate?

Answer 18

Interphase
Organelles including centrioles replicate during interphase

Question 19

How to count chromosomes

Answer 19

We count chromosomes by the centromere. A replicated DNA molecule consisted of two identical sister chromatids held together by one centromere

https://drive.google.com/file/d/1xEuhbSzn-GXVEnCZH17XvTIqVZ8Wesgo/view?usp=drivesdk